Nonvolatile semiconductor memory is widely used for storage in electronic devices such as personal computers (PCs), cellular telephones, digital cameras and personal digital assistants (PDAs). Such memory includes resistive random access memory (ReRAM), magnetic random access memory (MRAM) and phase-change random access memory (PCRAM), all of which utilize a variable resistance element as a memory cell.
In an ReRAM, the resistance of a variable resistance element that varies according to application of a voltage or current is used as memory information. If the variable resistance element is operated to perform a binary operation, for example, the low-resistance state of the variable resistance element is set to correspond to binary 1 and the high-resistance state thereof is set to correspond to binary 0. The operation of changing the state from the high-resistance state to the low-resistance state is referred to as “set” and the reverse operation is referred to as “reset”.
For example, if a metal oxide film is used as a resistance-change film, the voltage (set voltage) required for setting the resistance-change film is generally set higher than the voltage (reset voltage) required for resetting the same. Since an interconnection and a selection element are connected to a resistance-change film when a memory cell array is configured by using variable resistance elements, a large portion of voltages that have been applied to the interconnection and selection element is applied to the resistance-change film if the resistance of the resistance-change film is rapidly increased at the reset time. If the voltage applied to the resistance-change film immediately after resetting is higher than the set voltage, the resistance-change film is transited to the low-resistance state again and an erroneous operation occurs.
Generally, the set voltage and reset voltage of the resistance-change film, the resistance of the low-resistance state and the resistance of the high-resistance state have variations in the respective elements or they have variations in one element each time the switching operation is performed. For example, since a voltage applied to the resistance-change film immediately after resetting varies if the resistance of the high-resistance state varies, the possibility that an erroneous operation occurs becomes strong.
A writing method of a resistance-change memory has been disclosed in a reference (for example, PCT National Publication No. WO2009/034687).